Abstract
Three new amides, pipgulzarine (1), pipzorine (2), and piptahsine (3), have been isolated from the dried seeds of Piper nigrum Linn. along with nine known constituents: (2__E__,4__E__,8__Z__)‐N‐(isobutyl)eicosatrienamide, pellitorine, pipercide, piperine, stigmastanol, stigmasterol, decurrenal, stigmasterol 3‐O‐β‐D‐glucopyranoside, and 5,10(15)‐cadinen‐4‐ol. The structures of the new constituents have been established as (2__E,11__E__)‐12‐(benzo[1,3]dioxol‐5‐yl)‐N‐(2‐methylpropyl)dodeca‐2,11‐dienamide__ (1), (2__E,12__Z__)‐N‐(4‐methylpentyl)octadeca‐2,12‐dienamide__ (2), and (2__E,4__S__)‐4‐hydroxy‐N‐(2‐methylpropyl)hex‐2‐enamide__ (3). The structures of 1–3 were derived by spectral studies and chemical reactions, and by comparison of spectral data in the case of known constituents. Compounds 1 and 2, and most of the already known compounds, exhibited toxicity against fourth instar larvae of Aedes aegypti Liston. The isolated (Z) double bond in 2 was assigned on the basis of its EI‐MS fragmentation pattern and its reaction with OsO~4~. The (S) configuration at C(4) of 3 was determined by Horeau's method. This is the first report of the isolation of a 4‐methylpentylamide from P. nigrum, while shorter branched amides have been reported from this genus [1].